diff --git a/api/fx/storage/storage.go b/api/fx/storage/storage.go
index 691f3783..01a95c7f 100644
--- a/api/fx/storage/storage.go
+++ b/api/fx/storage/storage.go
@@ -2,22 +2,17 @@ package storage
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/tech/sendico/fx/storage/model"
 )
 
-type storageError string
-
-func (e storageError) Error() string {
-	return string(e)
-}
-
 var (
-	ErrQuoteExpired         = storageError("fx.storage: quote expired")
-	ErrQuoteConsumed        = storageError("fx.storage: quote consumed")
-	ErrQuoteNotFirm         = storageError("fx.storage: quote is not firm")
-	ErrQuoteConsumptionRace = storageError("fx.storage: quote consumption collision")
+	ErrQuoteExpired         = errors.New("fx.storage: quote expired")
+	ErrQuoteConsumed        = errors.New("fx.storage: quote consumed")
+	ErrQuoteNotFirm         = errors.New("fx.storage: quote is not firm")
+	ErrQuoteConsumptionRace = errors.New("fx.storage: quote consumption collision")
 )
 
 type Repository interface {